11/10/2008 @ 5:00PM

In Depth: Where Does Your Fast Food Come From?

Industrial Farm Animal Production

In the 1950s, the advent of nitrogen-based fertilizer allowed farmers to rapidly maximize their output. This was particularly true of corn crops. In 1940, a farmer could expect 70 to 80 bushels of corn per acre. Today, that number has reached 200 bushels. This corn, in turn, has been used to feed livestock and poultry for quick and efficient growth. In 2007, the U.S. produced 48.7 billion pounds of commercial red meat, 90.6 billion eggs and 8.1 billion chickens, according to the USDA.